What is SUBQUERY in SQL

subquery

A subquery is a query within a query for the same or different table. The inner query is enclosed in parentheses (). The result of the inner query would be given as input to the outer query. Subqueries enable you to write queries that select data rows for criteria that are actually developed while the … Read more

DBMS MCQ Questions and Answer Set-6

DBMS-MCQ

1-A Database Management System (DBMS) is A. Collection of interrelated data B. Collection of programs to access data C. Collection of data describing one particular enterprise D. All of the above 2. Which of the following is not a level of data abstraction? A. Physical Level B. Critical Level C. Logical Level D. View Level 3. Disadvantages of File … Read more

What is UNIQUE Constraint in SQL

UNIQUE_Constraint

The UNIQUE constraint uniquely identifies each row in a table. The restriction which unique enforces in the Uniqueness of values with respect to any column. The UNIQUE and PRIMARY KEY constraints both provide a guarantee for uniqueness for a column or set of columns. A PRIMARY KEY automatically has a UNIQUE key defined on it. … Read more

Integrity Constraints in DBMS | SQL

Integrity-Constraints

Integrity constraints in DBMS Integrity in data means maintaining and assure the accuracy and consistency of data over its entire life-cycle. Database Systems ensure data integrity through Integrity Constraints in DBMS that are used to restrict data that can be entered or modified in the database. Constraints are used to limit the type of data … Read more